(Adds details of Iranian letter)
VIENNA, Jan 31 (Reuters) - Iran has informed the U.N. nuclear agency that it plans to use more modern uranium enrichment centrifuges at its Natanz plant, a diplomat said on Thursday.
Such a step could enable Iran to refine uranium faster than it can at the moment and increase concerns in the West and Israel about the goals of Tehran nuclear programme.
The diplomat who declined to be identified, said Iran had informed the International Atomic Energy Agency of the plan in a letter dated Jan. 23.
The letter said that Iran would use the new centrifuges - a model called IR-2m - at a unit in the Natanz plant where Iran is enriching uranium to a fissile concentration of up to five percent.
Iran says it refines uranium to power a planned network of nuclear power stations. But the West fears that the material, if enriched much further to 90 percent, could be used for weapons. Iran says its nuclear programme has only peaceful goals.
The Islamic republic has for years been trying to develop more centrifuges that are more efficient than the breakdown-prone 1970s IR-1 models it now uses for production. (Reporting by Frederik Dahl; Editing by Jon Boyle)